This invention is directed to a slider pin release mechanism for a slider suspension system for a semi-trailer. Movable subframes, typically referred to as sliders, have been utilized on semi-trailers for many years. The slider is conventionally mounted on the underside of the trailer body and the trailer body is movable longitudinally relative to the slider to provide a means of variable load distribution on the axles. A trailer having a slider gains an advantage with respect to laws governing maximum axle load. Proper placement of the trailer body relative to the slider varies individual axle loads and redistributes the trailer load so that it is within legal limits. Once the trailer body is properly positioned, the trailer body is locked in place with the slider by a retractable pin mechanism, usually including four pins with two located on each side of the slider.
The retractable pin mechanism of the prior art was actuated by a pull rod accessible from a side of the trailer. The pull rod was connected through a crank, shaft and rod mechanism to the individual retractable pins located on opposite sides of the slider. When the vehicle operator wished to retract the pins in order to move the trailer body relative to the slider, the operator pulled the pull rod in an outwardly direction. This pulling required the application of considerable amount of force by the operator because the crank, shaft and rod mechanism provided relatively little mechanical advantage.
While the prior art slider suspension is effective in varying individual axle loads, it has several disadvantages. One disadvantage of the prior art slider suspension is the difficulty of retracting the pins once the retractable pin mechanism becomes corroded. A trailer is transported through all types of road and environmental conditions. Moisture and corrosive contaminants, such as salt, will often cover the retractable pin mechanism thus corroding the mechanism making the retractable pin mechanism very difficult to operate. The small mechanical advantage provided by the crank arm often proved to be insufficient to retract the pins.
Another disadvantage of the prior art slider suspension, is the lack of verification of the retraction of the pins in the inboard direction allowing the trailer to slide along the slider. Without verification that the pins are fully retracted, the operator may attempt to slide the trailer body relative to the slider with the pins only partially retracted thereby damaging the pin mechanism.
Another disadvantage of the prior art slider suspension, is the difficulty of re-engaging the pins with the semi-trailer frame when the slider was relocated to its new position. The operator was dependent on the small mechanical advantage provided by the pull rod (which had to be used as a push rod) and the individual compressed coil springs acting on each pin to reinsert it.
The present invention is directed generally to an improved slider pin mechanism for a slider suspension system of a vehicle semi-trailer.
An object of this invention is a slider pin mechanism which utilizes a handle and a ratchet gear mechanism to provide an increased mechanical advantage to enable an operator to more easily disengage slider pins to allow readjustment of the slider.
Another object of this invention is a slider pin mechanism which will positively indicate to an operator that the slider pins have been fully retracted.
Yet another object of this invention is a slider pin mechanism which assists the operator in re-engaging the slider pins when the slider suspension is positioned in its new location.
Other objects of the invention will be found in the following specification, claims and drawings.